A method for efficiently producing substrates for electronic parts generally includes forming a conductor on a ceramic member having dividing grooves and then dividing the ceramic member along the dividing grooves into a large number of pieces.
The dividing grooves in a ceramic member are dominantly formed by pressing a blade attached to a die against an unbaked ceramic green sheet. The unbaked ceramic green sheet is then baked, and as a result, a problem may occur in which the dimensional accuracy may be poor due to uneven contraction of the product during sintering. Furthermore, a large ceramic member is necessary to produce a large number of substrates for electronic parts at once. However, such a large ceramic member may have a serious problem with dimensional accuracy.
The dividing grooves are also formed by a method of applying laser beams to a work piece. Such a laser machining method includes a laser abrasion technique. In this method, the work piece is locally melted and vaporized by laser irradiation so that a part of the work piece can be removed. A groove can be formed by moving the laser beam across the work piece.
The ceramic member mainly includes a ceramic material as a main ceramic component and contains a sintering aid. Therefore, when the laser machining method is performed on the ceramic member, the laser-irradiated portion is instantaneously and explosively removed causing a large amount of the sintering aid to be vaporized and lost from the surface of the groove.
In conventional laser machining, grooves are formed at a temperature such that the main ceramic component is vaporized. Therefore, the content of a sintering aid which has a boiling point lower than that of the main ceramic component can be significantly reduced in a surface layer of the grooves in the ceramic member. In particular, a sintering aid such as silica or yttria can be significantly reduced, so that mutual bonding strength between ceramic grains of the main ceramic component is reduced. In this manner, shortage of the sintering aid can cause the surface layer of the grooves to have low strength. Therefore, there is a need for materials and methods of manufacturing that allow formation of high strength grooves.